89 isuzu pickup starting problems

[pataber]

4 cyl. 2.6L - EFI. Truck starts then dies 2-5 secs. later. All relays were tested indivdually , fuel pump is working, new fuel filter. Ignition switch and air flow sensor were changed. The main symptom is that the heater fan and the fuel pump don't come on until truck is started, they die when the truck does. The relays for these 2 aren't energizing when the switch is on like they should. I have a Hayne's book but the schematic is generic and just has the basic components on it. If I could find out where the power comes from for the fuel pump relay, I can find the problem. Any suggestions? Thanks, Pat.

[TREEMECH]

Welcome to the club! I have the exact problems with my 92 pickup. I replaced my fuel filter, fuel pump relay and air flow sensor. If you have the same problem as I did, try removing the charge relay. When I removed mine the truck started. I can also start my truck if I tap on the fuse and circuit breaker panel. As illogical as it may sound I believe the problem is in the alternator. I will be installing it momentarily. If it fixes the problem I will post. BTW what did you find to be the problem?

[Jman0033]

I am in the same boat. I am almost relieved i found this forum, but it appears that you havent posted since so that is a little discomforting. I am having almost the same problem. I bought my 91 pup, 2.6 4ez1, and built a new engine and swaped the old one. Long story short upon getting it back together i couldent get spark or the blower motor to come on. I found the same conclusion, when you pull the carge relay the blower comes back on, but i have yet to get it to fire. I ran it through the self diagnostic test and code 35 (power transitor unit- wiring or faulty) but this is bogus because the 4ez1 engine doesnt have an external transitor. I have swaped the coil, checked the fuel system and have been endlessly trying to find this supposed short. If you can shed any light i would appriciate it. Thanks

[spddeamon005]

i had about the same problem with my 92 pup when i swapped a newer engine into my truck... i couldn't get it spark but it turns out the O2 sensor plugin (the one in the intake manifold or around that area by the coil) is the same as the coil plugin... i accidently got the two swapped around and it wouldnt start... well i swapped it around and it started right up! try that... hope that helps you

[jackass#1]

most electric fuel pumps are wired in with the oil pressurre switch. this is so the truck wont start unless the switch detects oil pressure. found this out $300 dollars too late. check out the switch its worth checking out. if the gauge is still showing pressure dosent mean the pressure switch is working.

[creek88]

Originally Posted by Jman0033

I am in the same boat. I am almost relieved i found this forum, but it appears that you havent posted since so that is a little discomforting. I am having almost the same problem. I bought my 91 pup, 2.6 4ez1, and built a new engine and swaped the old one. Long story short upon getting it back together i couldent get spark or the blower motor to come on. I found the same conclusion, when you pull the carge relay the blower comes back on, but i have yet to get it to fire. I ran it through the self diagnostic test and code 35 (power transitor unit- wiring or faulty) but this is bogus because the 4ez1 engine doesnt have an external transitor. I have swaped the coil, checked the fuel system and have been endlessly trying to find this supposed short. If you can shed any light i would appriciate it. Thanks

I have the same problem with the spark. Did you get yours resolved? If so, how?

[ragen isuzu]

so i have a 90' isuzu pickup space cab with the 2.6 and it seems i have similar probs, mine still runs good most of the time, when it does act up, it acts like it want to die and some times i have to keep my foot on the gas to keep it going but a few mins later it will idle just fine. my oil pressure will start to drop below fifty. when it runs good its stays at fifty or more when given exra gas. when it runs like crap even with gas pushed im lucy to get it to fifty? im guessing it would be the oil sending unit? it has a newer o2 senser and a newer fuel pump and filter with less then 5000 on it
any ideas?